A. Field of the Invention
The present invention relates to a method for processing a plate-like carrying member to mount a shaft of a gear or the like. More particularly, the present invention relates to a method for forming one or more shaft fixing apertures having a function of stopping rotation in the plate-like carrying member.
B. Description of the Background Art
Generally, automatic transmissions of automobiles and other types of transmissions often employ planetary gear mechanisms therein. In conventional planetary gear mechanisms, the shafts of the pinions (planetary gears) are generally fixed to a carrier by fitting and caulking. In particular, one end of each of the pinion shafts is received in one aperture in the carrier.
In the prior art, however, the apertures in the carrier are typically holes with simple circular cross-sections, with the end of the pinion shafts having simple circular cross-sections such that the pinion shafts fit into the apertures of the carrier. Therefore, in these prior art devices, it is difficult to stop rotation of the pinion shaft with the apertures of the carrier. Moreover, it is difficult to stop axial movement of the pinion shafts within the apertures of the carrier.
In view of this, some prior art devices have already been proposed that use stepped apertures and stepped pinion shafts. The stepped portions of the apertures are formed at an inner peripheral surface of the shaft fixing aperture in the carrier, while the stepped portions of the pinion shafts are formed at an outer peripheral surface of the pinion shaft. The stepped portions, the apertures and the pinion shafts are engaged together for stopping rotational and axial movement of the pinion shafts within the shaft fixing apertures of the carrier.
In the structure already proposed, however, the shaft fixing apertures with the stepped portions are formed in the carrier by casting. Therefore, manufacturing of the carrier is quite time-consuming work and often expensive.